Issue: January 4, 2003

Pollarded trees

I toured several cities in Europe this fall and noticed that many of the street trees in those cities have been topped. I thought that was not good for the trees. Why do they do this?

The trees you saw were probably "pollarded", which looks like topping but differs in some significant ways. This procedure is done to allow the growing of trees in smaller streetscape settings and also as a matter of tradition. Pollarding of trees began hundreds of years ago as a way of producing annually renewed stove wood and weaving wood for baskets. The look of pollarded trees became accepted as a normal appearance of trees, so pollarding continues, especially when a formal garden appearance is desired. I hope by now you are wondering about the difference between topping and pollarding. In the case of proper pollarding, the branches that are cut are never more than one- to-two years old. In topping, much older and larger branches are cut. Only a few varieties of trees tolerate pollarding as a management method. The pollarding process does not severely circumvent the natural protective mechanism that protects the tree from disease and insects. Topping, on the other hand, totally defeats the protective mechanism of the tree. During the dormant season, you can see that all the new growth on a pollarded tree is small (one-to-two years old) and originates from the same area of the branches. Every one-to-two years, the sprouts are cut back to the same area of the branch stump where they originated. This results in knobby ends to the major branches from which the new sprouts grow each year. Topping is indeed not a recommended manner of pruning trees. Pollarding is okay as long as you are willing to assume the responsibility and expense to assure that it is done every one-to-two years for the life of the tree.

Houseplant winter fertilization

Should I fertilize my houseplants during the winter?

If your plants are receiving sufficient light and the location will allow for growth, you can fertilize your houseplants. Choose the type of fertilizer based on the type of plant. Plants grown for their foliage need fertilizer higher in nitrogen while flowering plants need more phosphorus. Read the label on the fertilizer container to determine which nutrients are available and their relative proportions. If your plants are becoming leggy because of low light and high temperatures, fertilization may increase the problem. If the space is limited, encouraging growth by fertilization will definitely add to the problem. Based on the type and needs of the plant, and also the growing conditions, you can determine whether fertilization is right for your houseplants.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!